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.TH "RBD" "8" "March 07, 2017" "dev" "Ceph"
.SH NAME
rbd \- manage rados block device (RBD) images
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.SH SYNOPSIS
.nf
\fBrbd\fP [ \-c \fIceph.conf\fP ] [ \-m \fImonaddr\fP ] [\-\-cluster \fIcluster name\fP]
[ \-p | \-\-pool \fIpool\fP ] [ \fIcommand\fP ... ]
.fi
.sp
.SH DESCRIPTION
.sp
\fBrbd\fP is a utility for manipulating rados block device (RBD) images,
used by the Linux rbd driver and the rbd storage driver for Qemu/KVM.
RBD images are simple block devices that are striped over objects and
stored in a RADOS object store. The size of the objects the image is
striped over must be a power of two.
.SH OPTIONS
.INDENT 0.0
.TP
.B \-c ceph.conf, \-\-conf ceph.conf
Use ceph.conf configuration file instead of the default /etc/ceph/ceph.conf to
determine monitor addresses during startup.
.UNINDENT
.INDENT 0.0
.TP
.B \-m monaddress[:port]
Connect to specified monitor (instead of looking through ceph.conf).
.UNINDENT
.INDENT 0.0
.TP
.B \-\-cluster cluster name
Use different cluster name as compared to default cluster name \fIceph\fP\&.
.UNINDENT
.INDENT 0.0
.TP
.B \-p pool\-name, \-\-pool pool\-name
Interact with the given pool. Required by most commands.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-no\-progress
Do not output progress information (goes to standard error by
default for some commands).
.UNINDENT
.SH PARAMETERS
.INDENT 0.0
.TP
.B \-\-image\-format format\-id
Specifies which object layout to use. The default is 2.
.INDENT 7.0
.IP \(bu 2
format 1 \- (deprecated) Use the original format for a new rbd image. This
format is understood by all versions of librbd and the kernel rbd module,
but does not support newer features like cloning.
.IP \(bu 2
format 2 \- Use the second rbd format, which is supported by
librbd and kernel since version 3.11 (except for striping). This adds
support for cloning and is more easily extensible to allow more
features in the future.
.UNINDENT
.UNINDENT
.INDENT 0.0
.TP
.B \-s size\-in\-M/G/T, \-\-size size\-in\-M/G/T
Specifies the size of the new rbd image or the new size of the existing rbd
image in M/G/T.  If no suffix is given, unit M is assumed.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-object\-size size\-in\-B/K/M
Specifies the object size in B/K/M.  Object size will be rounded up the
nearest power of two; if no suffix is given, unit B is assumed.  The default
object size is 4M, smallest is 4K and maximum is 32M.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-stripe\-unit size\-in\-B/K/M
Specifies the stripe unit size in B/K/M.  If no suffix is given, unit B is
assumed.  See striping section (below) for more details.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-stripe\-count num
Specifies the number of objects to stripe over before looping back
to the first object.  See striping section (below) for more details.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-snap snap
Specifies the snapshot name for the specific operation.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-id username
Specifies the username (without the \fBclient.\fP prefix) to use with the map command.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-keyring filename
Specifies a keyring file containing a secret for the specified user
to use with the map command.  If not specified, the default keyring
locations will be searched.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-keyfile filename
Specifies a file containing the secret key of \fB\-\-id user\fP to use with the map command.
This option is overridden by \fB\-\-keyring\fP if the latter is also specified.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-shared lock\-tag
Option for \fIlock add\fP that allows multiple clients to lock the
same image if they use the same tag. The tag is an arbitrary
string. This is useful for situations where an image must
be open from more than one client at once, like during
live migration of a virtual machine, or for use underneath
a clustered filesystem.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-format format
Specifies output formatting (default: plain, json, xml)
.UNINDENT
.INDENT 0.0
.TP
.B \-\-pretty\-format
Make json or xml formatted output more human\-readable.
.UNINDENT
.INDENT 0.0
.TP
.B \-o krbd\-options, \-\-options krbd\-options
Specifies which options to use when mapping or unmapping an image via the
rbd kernel driver.  krbd\-options is a comma\-separated list of options
(similar to mount(8) mount options).  See kernel rbd (krbd) options section
below for more details.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-read\-only
Map the image read\-only.  Equivalent to \-o ro.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-image\-feature feature\-name
Specifies which RBD format 2 feature should be enabled when creating
an image. Multiple features can be enabled by repeating this option
multiple times. The following features are supported:
.INDENT 7.0
.IP \(bu 2
layering: layering support
.IP \(bu 2
striping: striping v2 support
.IP \(bu 2
exclusive\-lock: exclusive locking support
.IP \(bu 2
object\-map: object map support (requires exclusive\-lock)
.IP \(bu 2
fast\-diff: fast diff calculations (requires object\-map)
.IP \(bu 2
deep\-flatten: snapshot flatten support
.IP \(bu 2
journaling: journaled IO support (requires exclusive\-lock)
.UNINDENT
.UNINDENT
.INDENT 0.0
.TP
.B \-\-image\-shared
Specifies that the image will be used concurrently by multiple clients.
This will disable features that are dependent upon exclusive ownership
of the image.
.UNINDENT
.INDENT 0.0
.TP
.B \-\-whole\-object
Specifies that the diff should be limited to the extents of a full object
instead of showing intra\-object deltas. When the object map feature is
enabled on an image, limiting the diff to the object extents will
dramatically improve performance since the differences can be computed
by examining the in\-memory object map instead of querying RADOS for each
object within the image.
.UNINDENT
.SH COMMANDS
.INDENT 0.0
.TP
.B \fBls\fP [\-l | \-\-long] [\fIpool\-name\fP]
Will list all rbd images listed in the rbd_directory object.  With
\-l, also show snapshots, and use longer\-format output including
size, parent (if clone), format, etc.
.TP
.B \fBdu\fP [\-p | \-\-pool \fIpool\-name\fP] [\fIimage\-spec\fP | \fIsnap\-spec\fP]
Will calculate the provisioned and actual disk usage of all images and
associated snapshots within the specified pool.  It can also be used against
individual images and snapshots.
.sp
If the RBD fast\-diff feature isn\(aqt enabled on images, this operation will
require querying the OSDs for every potential object within the image.
.TP
.B \fBinfo\fP \fIimage\-spec\fP | \fIsnap\-spec\fP
Will dump information (such as size and object size) about a specific rbd image.
If image is a clone, information about its parent is also displayed.
If a snapshot is specified, whether it is protected is shown as well.
.TP
.B \fBcreate\fP (\-s | \-\-size \fIsize\-in\-M/G/T\fP) [\-\-image\-format \fIformat\-id\fP] [\-\-object\-size \fIsize\-in\-B/K/M\fP] [\-\-stripe\-unit \fIsize\-in\-B/K/M\fP \-\-stripe\-count \fInum\fP] [\-\-image\-feature \fIfeature\-name\fP]... [\-\-image\-shared] \fIimage\-spec\fP
Will create a new rbd image. You must also specify the size via \-\-size.  The
\-\-stripe\-unit and \-\-stripe\-count arguments are optional, but must be used together.
.TP
.B \fBclone\fP [\-\-object\-size \fIsize\-in\-B/K/M\fP] [\-\-stripe\-unit \fIsize\-in\-B/K/M\fP \-\-stripe\-count \fInum\fP] [\-\-image\-feature \fIfeature\-name\fP] [\-\-image\-shared] \fIparent\-snap\-spec\fP \fIchild\-image\-spec\fP
Will create a clone (copy\-on\-write child) of the parent snapshot.
Object size will be identical to that of the parent image unless
specified. Size will be the same as the parent snapshot. The \-\-stripe\-unit
and \-\-stripe\-count arguments are optional, but must be used together.
.sp
The parent snapshot must be protected (see \fIrbd snap protect\fP).
This requires image format 2.
.TP
.B \fBflatten\fP \fIimage\-spec\fP
If image is a clone, copy all shared blocks from the parent snapshot and
make the child independent of the parent, severing the link between
parent snap and child.  The parent snapshot can be unprotected and
deleted if it has no further dependent clones.
.sp
This requires image format 2.
.TP
.B \fBchildren\fP \fIsnap\-spec\fP
List the clones of the image at the given snapshot. This checks
every pool, and outputs the resulting poolname/imagename.
.sp
This requires image format 2.
.TP
.B \fBresize\fP (\-s | \-\-size \fIsize\-in\-M/G/T\fP) [\-\-allow\-shrink] \fIimage\-spec\fP
Resizes rbd image. The size parameter also needs to be specified.
The \-\-allow\-shrink option lets the size be reduced.
.TP
.B \fBrm\fP \fIimage\-spec\fP
Deletes an rbd image (including all data blocks). If the image has
snapshots, this fails and nothing is deleted.
.TP
.B \fBexport\fP (\fIimage\-spec\fP | \fIsnap\-spec\fP) [\fIdest\-path\fP]
Exports image to dest path (use \- for stdout).
.TP
.B \fBimport\fP [\-\-image\-format \fIformat\-id\fP] [\-\-object\-size \fIsize\-in\-B/K/M\fP] [\-\-stripe\-unit \fIsize\-in\-B/K/M\fP \-\-stripe\-count \fInum\fP] [\-\-image\-feature \fIfeature\-name\fP]... [\-\-image\-shared] \fIsrc\-path\fP [\fIimage\-spec\fP]
Creates a new image and imports its data from path (use \- for
stdin).  The import operation will try to create sparse rbd images
if possible.  For import from stdin, the sparsification unit is
the data block size of the destination image (object size).
.sp
The \-\-stripe\-unit and \-\-stripe\-count arguments are optional, but must be
used together.
.TP
.B \fBexport\-diff\fP [\-\-from\-snap \fIsnap\-name\fP] [\-\-whole\-object] (\fIimage\-spec\fP | \fIsnap\-spec\fP) \fIdest\-path\fP
Exports an incremental diff for an image to dest path (use \- for stdout).  If
an initial snapshot is specified, only changes since that snapshot are included; otherwise,
any regions of the image that contain data are included.  The end snapshot is specified
using the standard \-\-snap option or @snap syntax (see below).  The image diff format includes
metadata about image size changes, and the start and end snapshots.  It efficiently represents
discarded or \(aqzero\(aq regions of the image.
.TP
.B \fBmerge\-diff\fP \fIfirst\-diff\-path\fP \fIsecond\-diff\-path\fP \fImerged\-diff\-path\fP
Merge two continuous incremental diffs of an image into one single diff. The
first diff\(aqs end snapshot must be equal with the second diff\(aqs start snapshot.
The first diff could be \- for stdin, and merged diff could be \- for stdout, which
enables multiple diff files to be merged using something like
\(aqrbd merge\-diff first second \- | rbd merge\-diff \- third result\(aq. Note this command
currently only support the source incremental diff with stripe_count == 1
.TP
.B \fBimport\-diff\fP \fIsrc\-path\fP \fIimage\-spec\fP
Imports an incremental diff of an image and applies it to the current image.  If the diff
was generated relative to a start snapshot, we verify that snapshot already exists before
continuing.  If there was an end snapshot we verify it does not already exist before
applying the changes, and create the snapshot when we are done.
.TP
.B \fBdiff\fP [\-\-from\-snap \fIsnap\-name\fP] [\-\-whole\-object] \fIimage\-spec\fP | \fIsnap\-spec\fP
Dump a list of byte extents in the image that have changed since the specified start
snapshot, or since the image was created.  Each output line includes the starting offset
(in bytes), the length of the region (in bytes), and either \(aqzero\(aq or \(aqdata\(aq to indicate
whether the region is known to be zeros or may contain other data.
.TP
.B \fBcp\fP (\fIsrc\-image\-spec\fP | \fIsrc\-snap\-spec\fP) \fIdest\-image\-spec\fP
Copies the content of a src\-image into the newly created dest\-image.
dest\-image will have the same size, object size, and image format as src\-image.
.TP
.B \fBmv\fP \fIsrc\-image\-spec\fP \fIdest\-image\-spec\fP
Renames an image.  Note: rename across pools is not supported.
.TP
.B \fBimage\-meta list\fP \fIimage\-spec\fP
Show metadata held on the image. The first column is the key
and the second column is the value.
.TP
.B \fBimage\-meta get\fP \fIimage\-spec\fP \fIkey\fP
Get metadata value with the key.
.TP
.B \fBimage\-meta set\fP \fIimage\-spec\fP \fIkey\fP \fIvalue\fP
Set metadata key with the value. They will displayed in \fIimage\-meta list\fP\&.
.TP
.B \fBimage\-meta remove\fP \fIimage\-spec\fP \fIkey\fP
Remove metadata key with the value.
.TP
.B \fBobject\-map rebuild\fP \fIimage\-spec\fP | \fIsnap\-spec\fP
Rebuilds an invalid object map for the specified image. An image snapshot can be
specified to rebuild an invalid object map for a snapshot.
.TP
.B \fBsnap ls\fP \fIimage\-spec\fP
Dumps the list of snapshots inside a specific image.
.TP
.B \fBsnap create\fP \fIsnap\-spec\fP
Creates a new snapshot. Requires the snapshot name parameter specified.
.TP
.B \fBsnap rollback\fP \fIsnap\-spec\fP
Rollback image content to snapshot. This will iterate through the entire blocks
array and update the data head content to the snapshotted version.
.TP
.B \fBsnap rm\fP \fIsnap\-spec\fP
Removes the specified snapshot.
.TP
.B \fBsnap purge\fP \fIimage\-spec\fP
Removes all snapshots from an image.
.TP
.B \fBsnap protect\fP \fIsnap\-spec\fP
Protect a snapshot from deletion, so that clones can be made of it
(see \fIrbd clone\fP).  Snapshots must be protected before clones are made;
protection implies that there exist dependent cloned children that
refer to this snapshot.  \fIrbd clone\fP will fail on a nonprotected
snapshot.
.sp
This requires image format 2.
.TP
.B \fBsnap unprotect\fP \fIsnap\-spec\fP
Unprotect a snapshot from deletion (undo \fIsnap protect\fP).  If cloned
children remain, \fIsnap unprotect\fP fails.  (Note that clones may exist
in different pools than the parent snapshot.)
.sp
This requires image format 2.
.TP
.B \fBmap\fP [\-o | \-\-options \fIkrbd\-options\fP ] [\-\-read\-only] \fIimage\-spec\fP | \fIsnap\-spec\fP
Maps the specified image to a block device via the rbd kernel module.
.TP
.B \fBunmap\fP [\-o | \-\-options \fIkrbd\-options\fP ] \fIimage\-spec\fP | \fIsnap\-spec\fP | \fIdevice\-path\fP
Unmaps the block device that was mapped via the rbd kernel module.
.TP
.B \fBshowmapped\fP
Show the rbd images that are mapped via the rbd kernel module.
.TP
.B \fBnbd map\fP [\-\-device \fIdevice\-path\fP] [\-\-read\-only] \fIimage\-spec\fP | \fIsnap\-spec\fP
Maps the specified image to a block device via the rbd\-nbd tool.
.TP
.B \fBnbd unmap\fP \fIdevice\-path\fP
Unmaps the block device that was mapped via the rbd\-nbd tool.
.TP
.B \fBnbd list\fP
Show the list of used nbd devices via the rbd\-nbd tool.
.TP
.B \fBstatus\fP \fIimage\-spec\fP
Show the status of the image, including which clients have it open.
.TP
.B \fBfeature disable\fP \fIimage\-spec\fP \fIfeature\-name\fP\&...
Disables the specified feature on the specified image. Multiple features can
be specified.
.TP
.B \fBfeature enable\fP \fIimage\-spec\fP \fIfeature\-name\fP\&...
Enables the specified feature on the specified image. Multiple features can
be specified.
.TP
.B \fBlock list\fP \fIimage\-spec\fP
Show locks held on the image. The first column is the locker
to use with the \fIlock remove\fP command.
.TP
.B \fBlock add\fP [\-\-shared \fIlock\-tag\fP] \fIimage\-spec\fP \fIlock\-id\fP
Lock an image. The lock\-id is an arbitrary name for the user\(aqs
convenience. By default, this is an exclusive lock, meaning it
will fail if the image is already locked. The \-\-shared option
changes this behavior. Note that locking does not affect
any operation other than adding a lock. It does not
protect an image from being deleted.
.TP
.B \fBlock remove\fP \fIimage\-spec\fP \fIlock\-id\fP \fIlocker\fP
Release a lock on an image. The lock id and locker are
as output by lock ls.
.TP
.B \fBbench\-write\fP [\-\-io\-size \fIsize\-in\-B/K/M/G/T\fP] [\-\-io\-threads \fInum\-ios\-in\-flight\fP] [\-\-io\-total \fIsize\-in\-B/K/M/G/T\fP] [\-\-io\-pattern seq | rand] \fIimage\-spec\fP
Generate a series of writes to the image and measure the write throughput and
latency.  If no suffix is given, unit B is assumed for both \-\-io\-size and
\-\-io\-total.  Defaults are: \-\-io\-size 4096, \-\-io\-threads 16, \-\-io\-total 1G,
\-\-io\-pattern seq.
.UNINDENT
.SH IMAGE AND SNAP SPECS
.nf
\fIimage\-spec\fP is [\fIpool\-name\fP]/\fIimage\-name\fP
\fIsnap\-spec\fP  is [\fIpool\-name\fP]/\fIimage\-name\fP@\fIsnap\-name\fP
.fi
.sp
.sp
The default for \fIpool\-name\fP is "rbd".  If an image name contains a slash
character (\(aq/\(aq), \fIpool\-name\fP is required.
.sp
You may specify each name individually, using \-\-pool, \-\-image and \-\-snap
options, but this is discouraged in favor of the above spec syntax.
.SH STRIPING
.sp
RBD images are striped over many objects, which are then stored by the
Ceph distributed object store (RADOS).  As a result, read and write
requests for the image are distributed across many nodes in the
cluster, generally preventing any single node from becoming a
bottleneck when individual images get large or busy.
.sp
The striping is controlled by three parameters:
.INDENT 0.0
.TP
.B object\-size
The size of objects we stripe over is a power of two. It will be rounded up the nearest power of two.
The default object size is 4 MB, smallest is 4K and maximum is 32M.
.UNINDENT
.INDENT 0.0
.TP
.B stripe_unit
Each [\fIstripe_unit\fP] contiguous bytes are stored adjacently in the same object, before we move on
to the next object.
.UNINDENT
.INDENT 0.0
.TP
.B stripe_count
After we write [\fIstripe_unit\fP] bytes to [\fIstripe_count\fP] objects, we loop back to the initial object
and write another stripe, until the object reaches its maximum size.  At that point,
we move on to the next [\fIstripe_count\fP] objects.
.UNINDENT
.sp
By default, [\fIstripe_unit\fP] is the same as the object size and [\fIstripe_count\fP] is 1.  Specifying a different
[\fIstripe_unit\fP] requires that the STRIPINGV2 feature be supported (added in Ceph v0.53) and format 2 images be
used.
.SH KERNEL RBD (KRBD) OPTIONS
.sp
Most of these options are useful mainly for debugging and benchmarking.  The
default values are set in the kernel and may therefore depend on the version of
the running kernel.
.sp
Per client instance \fIrbd map\fP options:
.INDENT 0.0
.IP \(bu 2
fsid=aaaaaaaa\-bbbb\-cccc\-dddd\-eeeeeeeeeeee \- FSID that should be assumed by
the client.
.IP \(bu 2
ip=a.b.c.d[:p] \- IP and, optionally, port the client should use.
.IP \(bu 2
share \- Enable sharing of client instances with other mappings (default).
.IP \(bu 2
noshare \- Disable sharing of client instances with other mappings.
.IP \(bu 2
crc \- Enable CRC32C checksumming for data writes (default).
.IP \(bu 2
nocrc \- Disable CRC32C checksumming for data writes.
.IP \(bu 2
cephx_require_signatures \- Require cephx message signing (since 3.19,
default).
.IP \(bu 2
nocephx_require_signatures \- Don\(aqt require cephx message signing (since
3.19).
.IP \(bu 2
tcp_nodelay \- Disable Nagle\(aqs algorithm on client sockets (since 4.0,
default).
.IP \(bu 2
notcp_nodelay \- Enable Nagle\(aqs algorithm on client sockets (since 4.0).
.IP \(bu 2
cephx_sign_messages \- Enable message signing (since 4.4, default).
.IP \(bu 2
nocephx_sign_messages \- Disable message signing (since 4.4).
.IP \(bu 2
mount_timeout=x \- A timeout on various steps in \fIrbd map\fP and \fIrbd unmap\fP
sequences (default is 60 seconds).  In particular, since 4.2 this can be used
to ensure that \fIrbd unmap\fP eventually times out when there is no network
connection to a cluster.
.IP \(bu 2
osdkeepalive=x \- OSD keepalive timeout (default is 5 seconds).
.IP \(bu 2
osd_idle_ttl=x \- OSD idle TTL (default is 60 seconds).
.UNINDENT
.sp
Per mapping (block device) \fIrbd map\fP options:
.INDENT 0.0
.IP \(bu 2
rw \- Map the image read\-write (default).
.IP \(bu 2
ro \- Map the image read\-only.  Equivalent to \-\-read\-only.
.IP \(bu 2
queue_depth=x \- queue depth (since 4.2, default is 128 requests).
.IP \(bu 2
lock_on_read \- Acquire exclusive lock on reads, in addition to writes and
discards (since 4.9).
.UNINDENT
.sp
\fIrbd unmap\fP options:
.INDENT 0.0
.IP \(bu 2
force \- Force the unmapping of a block device that is open (since 4.9).  The
driver will wait for running requests to complete and then unmap; requests
sent to the driver after initiating the unmap will be failed.
.UNINDENT
.SH EXAMPLES
.sp
To create a new rbd image that is 100 GB:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd create mypool/myimage \-\-size 102400
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To use a non\-default object size (8 MB):
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd create mypool/myimage \-\-size 102400 \-\-object\-size 8M
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To delete an rbd image (be careful!):
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd rm mypool/myimage
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To create a new snapshot:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd snap create mypool/myimage@mysnap
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To create a copy\-on\-write clone of a protected snapshot:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd clone mypool/myimage@mysnap otherpool/cloneimage
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To see which clones of a snapshot exist:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd children mypool/myimage@mysnap
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To delete a snapshot:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd snap rm mypool/myimage@mysnap
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To map an image via the kernel with cephx enabled:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd map mypool/myimage \-\-id admin \-\-keyfile secretfile
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To map an image via the kernel with different cluster name other than default \fIceph\fP\&.
.INDENT 0.0
.INDENT 3.5
rbd map mypool/myimage \-\-cluster \fIcluster name\fP
.UNINDENT
.UNINDENT
.sp
To unmap an image:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd unmap /dev/rbd0
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To create an image and a clone from it:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd import \-\-image\-format 2 image mypool/parent
rbd snap create mypool/parent@snap
rbd snap protect mypool/parent@snap
rbd clone mypool/parent@snap otherpool/child
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To create an image with a smaller stripe_unit (to better distribute small writes in some workloads):
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd create mypool/myimage \-\-size 102400 \-\-stripe\-unit 65536B \-\-stripe\-count 16
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To change an image from one image format to another, export it and then
import it as the desired image format:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd export mypool/myimage@snap /tmp/img
rbd import \-\-image\-format 2 /tmp/img mypool/myimage2
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To lock an image for exclusive use:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd lock add mypool/myimage mylockid
.ft P
.fi
.UNINDENT
.UNINDENT
.sp
To release a lock:
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
rbd lock remove mypool/myimage mylockid client.2485
.ft P
.fi
.UNINDENT
.UNINDENT
.SH AVAILABILITY
.sp
\fBrbd\fP is part of Ceph, a massively scalable, open\-source, distributed storage system. Please refer to
the Ceph documentation at \fI\%http://ceph.com/docs\fP for more information.
.SH SEE ALSO
.sp
\fBceph\fP(8),
\fBrados\fP(8)
.SH COPYRIGHT
2010-2014, Inktank Storage, Inc. and contributors. Licensed under Creative Commons BY-SA
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